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The high-capacity DNA sequencer being loaded by geneticists Curt Van Tassell (left) and Tad Sonstegard will increase the number of genetic markers available for screening in livestock populations. Click the image for more information about it.

New Technique to Tap Bulls for Breeding

A project involving Agricultural Research Service (ARS) and collaborating scientists could open the door to a new, genomics-based approach to identifying elite bulls.

Now carried out by the artificial insemination (AI) industry, progeny testing characterizes the genetic merit of a bull. But progeny testing is time-consuming and expensive. Each year, AI organizations test 1,200 Holstein dairy bulls at a cost of about $30 million.

Records on performance and conformation are combined with pedigree information using sophisticated statistical methods to determine the genetic merit of animals used for breeding. But Van Tassell and ARS collaborators Tad Sonstegard and George Wiggans are investigating an approach called "genome-enhanced selection" which could replace progeny testing and cost around $500 per bull.

Central to the approach is obtaining information on DNA sequence variations, or genetic markers, called single nucleotide polymorphisms (SNPs). Efforts are under way to develop a test to allow close examination of 55,000 SNPs from a select group of 4,000 animals representing several dairy breeds and an ARS research population.

The scientists will then correlate the SNP data to observable, or phenotypic, traits of interest so that eventually dairy producers can use information derived from the markers to selectively breed animals based on genetic merit.